Oct 3 (Reuters) - U.S. holiday sales will increase 3.6 percent to 4 percent, getting a boost from an extra selling day and rising consumer confidence, according to a forecast from a leading retail industry group.

The guidance range, however, tipped slightly lower than last year’s holiday season sales growth of 4 percent.

The National Retail Federation (NRF) forecast sales for the last two months of the year between $678.75 billion and $682 billion, excluding autos, gasoline and dining out.

“While recent hurricanes are not expected to have a significant long-term effect on the economy, NRF is issuing this year’s forecast as a range rather than the usual fixed percentage because the impact of the storms on economic indicators has made it difficult to make a more precise forecast,” the industry body said in a statement.

NRF’s forecast is one of the most closely watched benchmarks ahead of the holiday season, which can account for 20 percent to 40 percent of annual sales for many retailers.

Christmas falls 32 days after Thanksgiving this year, one extra day than last year, and is on a Monday instead of Sunday, giving consumers a full weekend to complete their shopping, the industry body said in its report.

U.S. consumer confidence has also been strengthening over this past year, due to a labor market that is churning out jobs, rising home prices and stock markets that are hovering at record highs.

Non-store sales, which include online sales and those from kiosks, are expected to rise 11 to 15 percent to about $140 billion, the NRF said. In 2016, those sales rose 12.6 percent.

NRF’s forecast on Tuesday follows estimates from firms including, Deloitte and AlixPartners, which anticipate holiday season sales growth between 3.8 percent and 4.5 percent, due to higher online spending and a tightening job market.

Big U.S. retail stocks, including Macy’s Inc and Target Corp, were down marginally in early trading on Wall Street, in contrast with the S&P 500 consumer discretionary index, which was up 0.2 percent. (Reporting by Siddharth Cavale and Sruthi Ramakrishnan in Bengaluru; Editing by Bernard Orr)